The Federal Water Pollution Control Act of 1948 included some of the first major laws to address water pollution in the United States. This act was amended in 1972 to address growing concerns and continued degradation of U.S. waters, and the amended act commonly became known as the Clean Water Act. While initially only addressing point sources, later research and other factors prompted congress to address stormwater pollution via the Water Quality Act of 1987. Through this act, point and non-point source pollutants are regulated through the National Pollutant Discharge Elimination System permit program. One requirement of this program is for municipalities, developers, and other industrial dischargers to implement various minimum control measures or Best Management Practices (“BMPs”). One of these minimum control measures involves providing post-construction or structural BMPs. Structural BMPs are designed to manage the quantity of and to improve the quality of stormwater runoff. Such structural BMPs can generally be divided into two categories: Quality Control BMPs and Quantity Control BMPs. One or both of these types of Structural BMPs can be implicated when it comes to constructing and managing buildings, parking lots, roads, and various other developments and land improvements.
Developing land or improving existing developments thereupon can create extra burdens with respect to stormwater runoff in the area. Impermeable surfaces such as roofs, roads, parking lots, and the like can increase the volume and velocity of stormwater runoff, particularly in comparison with ordinary undeveloped land having soil and other natural components that can adsorb and contain the stormwater therein. This increase in the volume and velocity of the runoff can erode stream beds and channels, and also inundate municipal stormwater infrastructure. Early BMPs for controlling the volume and velocity of stormwater runoff consisted of above ground retention ponds that detained stormwater routed there via storm drain conveyance systems. As ponds fell out of favor due to safety and vector concerns, and as land costs escalated, retention systems began to be constructed underground instead.
It is generally well accepted that underground stormwater detention systems are preferable in many urban and well developed areas. The use of such systems allows for other uses of the actual surface regions, and also reduces safety hazards such as water dangers, mosquito breeding opportunities, and the like. Initial underground water detention systems were designed from pipe or large concrete structures, such as box culverts. Subsequent iterations of stormwater retention systems consisted of arched chambers made of plastic or concrete. Some of these systems consist of modular plastic crates or boxes, while others consist of large modular concrete boxes. Various further details regarding such modern underground stormwater retention systems can be found at, for example, U.S. Pat. No. 7,344,335 and European Patent No. EP 1818463 A1, both of which are incorporated by reference herein for such purposes.
Unfortunately, such underground water detention systems do have drawbacks and restrictions for those that implement them. For example, the more common concrete types of systems tend to involve the use of huge and bulky modular pieces that are often installed by way of a crane or other heavy construction equipment. The alternative plastic types of systems tend to be weaker and more prone to failure or other problems, such that these systems are not seen as big improvements over the huge concrete counterparts. With many types of both of the current concrete and plastic systems, such as that which is found in the foregoing examples, any modular nature involves the repetitive use of the same or similar self-sufficient and independent “building block” types of component. Accordingly, there tends to be little overall structural integrity or load sharing across an entire system of independent modular blocks stacked with each other. Furthermore, internal volumes that could be used to contain more fluid are instead used for redundant and unneeded ceilings, floors, and walls of the independent modular blocks that form the overall structure.
While various systems and techniques for capturing and retaining stormwater runoff have generally been adequate in the past, there is always a desire for improvement. To that end, it would be desirable to have improved underground stormwater capture and retention systems, and in particular for such systems to maintain overall strength while having greater fluid retention capacities per unit volumes, having better overall structural integrity, and being buildable without the use of heavy machinery.